1. Field of the Invention
This invention relates to printing on textiles, and more particularly to a printing apparatus and method for ink jet printing on textiles.
2. Description of the Related Art
Some of the current methods for printing on textiles include roller printing, screen-printing and transfer printing. These methods require the preparation of print or screen plates, which can take 2 to 3 weeks and can be very expensive. There are additional factors of time, labor and material contributing to initial cost, such as set-up of screens or rolls to determine pattern registration and xe2x80x9cstrike offsxe2x80x9d to evaluate the color accuracy. As a result, these methods are not cost efficient for printing one of a kind or small quantities of textiles. They are more commonly used for printing large quantities of a textile where the cost of preparing the plates can be spread over the entire quantity. However, one of the problems with printing large quantities of a textile is that the period for a particular fashion is often short. A change in fashion can lead to large, wasted stockpiles of out-of-fashion printed textiles. Also, there is a need to produce one-of-a-kind textiles such as haute couture fashion. Using the current methods, the cost of printing these small quantities is extremely high.
These problems have created interest in low cost methods and devices for printing on textiles that would be practical for printing small quantities. There is also interest in a method or device that does not have the 2-3 week time delay associated with preparation of the plates. The additional factors described above could extend the delay for months. This necessitates the fashion driven investor to take risks in pattern and color development to get the product to market on time.
Textile printing by ink jet printers has been proposed for printing small quantities. However, ink jet printers use low viscosity ink and the high viscosity ink that is conventionally used to print on textiles cannot be used in conventional ink jet printers because it does not properly flow through the ink jet nozzles. Also, low viscosity inks deposited on textiles are prone to spreading because textiles generally do not effectively retain ink. This problem is compounded by the fact that ink jets deposit only a small amount of ink on the textile for a particular pattern so the pattern easily abrades, washes away or fades. Considerable difficulties have been encountered in providing ink jet printed textiles with patterns that are durable, vibrant and do not fade from washing or exposure to the sun.
Various textile coatings and treatments have been applied to textiles to address these problems. For example, compounds such as starch, cellulose, gum arabic, and polyvinyl acetate have been placed on textiles before ink jet printing to reduce spreading or fading of the ink. Although an improvement, the ink jet patterns are still not as sharp as patterns produced by conventional methods and washing or exposure to the sun can result in significant color fading. Also, these treatments are usually applied at a location remote from the printer, where the textile is also dried and re-rolled. This can add time and expense to the printing process.
Applying a protective polymer coating after printing has also been used as a temporary solution. However, this requires a separate off-line process and has not been particularly effective. Often it causes the ink to bleed along the textile fibers and reduces print resolution. Also, the additional processing adds significant cost and minimizes the advantage of the rapid turn around that ink jet printing could provide.
Heat set or radiation cured inks have been used with ink-jet printers but this adds another step in the process, which adds cost and time and reduces the advantage of ink-jet printing for fast turn-around. Furthermore, these inks cause the textile to have a poor feel or texture because they form a stiff surface on curing.
Other treatments have been developed to improve the waterfastness of ink jet printed textiles. U.S. Pat. No. 4,702,742 to Kazuo discloses a method for ink jet printing textiles wherein an acceptor for the ink is deposited on the textile prior to printing, with the preferred acceptor being a water-soluble natural or synthetic polymer. Aqueous ink is then deposited on the textile by ink jet printing. The method includes the optional step of fixing the dye in the ink.
U.S. Pat. No. 6,001,137 to Alfekri et al. also discloses a method for ink jet printing of textiles wherein the textile is treated with a polymer or copolymer of epihalohydrin prior to ink jet printing. A softener such as tetraalkylammonium salt may also be deposited on the textile to give it a soft feel, and a cationic binder may also be deposited on the textile.
U.S. Pat. No. 5,853,861 to Held, discloses an ink/textile combination for ink jet printing patterns on a textile with improved durability and waterfastness. The ink contains an aqueous carrier, a pigment and a polymer having acid, base, epoxy or hydroxy functional moieties. The textile contains hydroxyl, amine, amido or carboxyl groups and a crosslinking agent, wherein upon exposure of the printed image to an external energy source, the crosslinking agent reacts with the textile and the polymer in the ink.
U.S. Pat. No. 5,698,478 to Yamamoto et al., discloses an ink jet printing cloth and printing process that improves the depth and brightness of the patterns printed on the cloth while not staining the cloth with a pre treating cationic substance. The ink jet cloth is composed mainly of cellulose fiber that contains 0.1 to 50% by weight of cationic substance, 0.01 to 5% by weight of an alkaline substance and 0.01 to 20% by weight of an ammonium salt of a polyvalent acid.
The primary disadvantage of these methods and products is that they require additional steps of preparing the textile before ink jet printing. This can require applying the substance to the textile and drying the textile (if necessary) at a remote location, adding time and expense. Post-treatments are also commonly applied and dried at a remote location, which can also add time and expense.
The present invention provides a new printing apparatus and method for ink jet printing on textiles wherein the steps of pre-treating, ink jet printing, and post-treating the textile takes place at the ink jet printer. This provides ink jet printing of textiles in one step and at one location, eliminating the time and expense incurred in the remote application of post- or pre-treat substances and the related drying and re-rolling. The invention also results in patterns that are more durable and fade resistant than conventional ink jet printed textiles. The pattern can also have better print resolution and brighter colors.
The new method includes the steps of applying a pre-treat to the textile, evaporating excess water from the pre-treat, ink jet printing a pattern on the pre-treated textile, evaporating water from the ink in the pattern, applying a binder/post-treat to the pattern and curing the binder. Alternatively, the pre-treatment and pre-treatment water evaporation steps can be omitted by ink jet printing on a textile that has already been pre-treated. The textile still goes through the steps of having the water from the ink evaporated, and the binder/post-treat applied and cured.
The new printing apparatus is arranged so that a scoured and/or bleached textile known as xe2x80x9cprepared for printingxe2x80x9d (PFP) textile can be fed into it with the new apparatus having a first depositing assembly to apply a pre-treat aqueous solution to the textile. A first evaporation assembly is arranged to evaporate most or all of the water from the pre-treated textile as it passes. An ink jet printer then accepts the pre-treated textile and prints the desired pattern on it. A second evaporation assembly is positioned at the output of the printer to evaporate water from the ink in the pattern. A second application device then applies a binder/post-treat solution to the printed textile and a third evaporation assembly dries and cures the binder/post-treat. In a preferred embodiment the evaporation assemblies dry the solutions and ink, and cure the binder/post-treat by applying heat to the textile.
The new apparatus can have feeders and rollers at its input and output so that the PFP textile can be automatically fed into the new printer and rolled immediately after printing and curing. The pattern to be printed on the textile is electronically loaded into the printer, preferably from a computer over a standard data bus. The pattern can be loaded into the computer from a variety of peripheral devices such as digital cameras or scanners, or over a data network such as the Internet.
The new apparatus and method can be used to print large and small quantities of textiles quickly and inexpensively. They are particularly applicable to printing relatively small quantities or series of textiles where small changes are required between each step such as printing different names and logos. It can also be used to match and print antique, damaged or faded textiles, to print sampling patterns on textiles for the fashion industry, or to print images on T-shirts and other novelty items. Conventional printing systems are limited to the size or repeat and the number of colors in the patterns. The invention provides a significant improvement over conventional methods. New and original designs can be produced from the computer onto finished fabrics in minutes, and color changes and repeat size alterations can be created in an equally brief time period.
These and other further features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings, in which: